Magnesium-zinc ferrite material and preparation method thereof

Abstract

The invention provides a magnesium-zinc ferrite material and a preparation method thereof, and the preparation method comprises the following steps: step A, crushing a nickel-zinc waste magnetic core to obtain a cooked blank; step B, mixing iron oxide, zinc oxide, magnesium oxide and copper oxide to obtain a raw material mixture; c, the cooked blank and the raw material mixture are subjected to primary sanding, and a primary sanding material is obtained; d, the primary sanding material is pre-sintered, and a pre-sintered material is obtained; step E, carrying out secondary sanding on the pre-sintered material, adding an adhesive in the secondary sanding process, and then carrying out spray drying granulation to obtain a granular material; and step F, carrying out compression molding on the granules, and sintering to obtain the magnesium-zinc ferrite material. By adopting the preparation method disclosed by the invention, the frequency characteristic, the Curie temperature, the sintering density and the anti-electromagnetic interference capability of the magnesium-zinc ferrite material can be improved, the production cost of the ferrite can be greatly reduced, and the market competitiveness is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic materials, and relates to a magnesium-zinc ferrite material and a preparation method thereof. Background Art

[0002] In today's society, we have entered the era of electronic information. Whether it is the household smart appliances in the consumer electronics field or the high-speed development of various industries such as photovoltaics, energy storage, automotive electronics, mobile satellite communications, and aerospace in the new energy field, the requirements for electronic products are increasingly trending towards high speed, wide frequency band, high sensitivity, and high density, etc. However, this will lead to an increasingly serious electromagnetic interference phenomenon. If not handled well, it will affect the normal operation of the system and even damage components.

[0003] People usually use the impedance characteristics of ferrite to solve electromagnetic interference problems. However, due to its high magnetic permeability, although the manganese-zinc ferrite has a large impedance in the KHz frequency band, due to its small resistivity, the loss increases due to eddy currents in the ferrite in the MHz frequency band. Therefore, it is difficult to be applied at frequencies above 10 MHz; the existing nickel-zinc ferrite can be applied in the frequency band of 10 MHz to 1000 MHz due to its high resistivity and low high-frequency loss. However, the nickel-zinc ferrite needs to use expensive NiO raw materials, and the content of NiO is large, and the price of NiO raw materials remains high, resulting in a high cost of nickel-zinc ferrite and no market competitiveness.

[0004] Relatively speaking, the price of MgO raw materials is much lower than that of NiO, so the cost of magnesium-zinc ferrite is relatively low. However, due to the high sintering temperature of the magnesium-zinc ferrite prepared by the existing process, it is not conducive to energy conservation and consumption reduction, and it has a low magnetic permeability, poor frequency characteristics, and a low Curie temperature, and the performance effect is not ideal, resulting in the inability to meet the requirements for a wide frequency band and high Curie temperature in fields such as automotive electronics, network communication, and aerospace during use. Therefore, in order to solve the above problems, there is an urgent need for a soft magnetic material that can meet the high-frequency application requirements of the market in the range of 10 MHz to 1000 MHz, has a relatively low cost, and has market competitiveness.

[0005] CN105541316A discloses "a manganese-zinc ferrite material for anti-EMI and a preparation method thereof". This invention has characteristics such as high saturation magnetic induction intensity Bs and high Curie temperature Tc, but its high-frequency impedance performance is not good and it cannot be used in high-frequency environments above 10 MHz.

[0006] CN107382300A discloses a nickel-zinc soft magnetic ferrite material and its preparation method. The ferrite components of this patent are 45-62 mol% of Fe2O3, 20-35 mol% of ZnO, and 15-25 mol% of NiO. The additives are 1-5 mol% of CuO, 0.5-9.5 mol% of Co2O3, 0.5-5 mol% of CaCO3, 0.5-5.5 mol% of V2O5, and 0.5-6.5 mol% of SnO2. The magnetic permeability can reach 1300 at 10 kHz. Although it achieves broadband high magnetic permeability, the content of expensive NiO in the formula is greater than 15 mol%, which is not conducive to cost reduction and lacks market competitiveness.

[0007] CN100353468C discloses an anti-interference magnesium-zinc ferrite and its preparation method. In this patent, three main components, namely magnesium oxide (8-27 moL%), zinc oxide (7-27 moL%), and iron oxide (30-36.7 moL%), are proportioned and pre-fired at 1000-1200 degrees, and then a variety of auxiliary additives are added to finally obtain a spray granulation material. After being pressed into a sample ring, it is sintered at 1250-1350 degrees. The magnetic permeability of the finally obtained sample ring is about 240-360, and the Curie temperature is about 120 degrees. Although MgO is used to replace NiO, the raw material cost is reduced, but its frequency characteristics are poor.

[0008] CN1814839 discloses a magnesium-zinc-based ferrite and its preparation method. In this patent, three main components, namely magnesium oxide (21-25.8 moL%), zinc oxide (23-27 moL%), and iron oxide (47.5-52.3 moL%), are proportioned and pre-fired at 850-1000 degrees, and then a variety of auxiliary additives are added to finally obtain a spray granulation material. After being pressed into a sample ring, it is sintered at 1050-1200 degrees. The magnetic permeability of the finally obtained sample ring is about 350, and the Curie temperature is about 150 degrees. Although MgO is used to replace NiO, the raw material cost is reduced, but its frequency characteristics are not ideal.

[0009] Therefore, it is urgent to solve the problem that soft magnetic materials cannot simultaneously meet the high-frequency application requirements of 10 MHz to 1000 MHz and the low-cost requirements. Summary of the Invention

[0010] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a magnesium-zinc ferrite material and its preparation method. The present invention uses nickel core waste magnetic cores as part of the raw materials, and cooperates with four main components, namely magnesium oxide, zinc oxide, iron oxide, and copper oxide. Through a specific manufacturing process, it can not only improve the frequency characteristics, Curie temperature, sintering density, and anti-electromagnetic interference ability of the magnesium-zinc ferrite material, but also greatly reduce the production cost of the ferrite magnetic core and improve the market competitiveness.

[0011] To achieve this purpose, the present invention adopts the following technical solutions:

[0012] In a first aspect, the present invention provides a preparation method of a magnesium zinc ferrite material, and the preparation method includes:

[0013] Step A: Crushing the nickel zinc waste magnetic core to obtain a cooked blank;

[0014] Step B: Mixing iron oxide (Fe2O3), zinc oxide (ZnO), magnesium oxide (MgO) and copper oxide (CuO) to obtain a raw material mixture;

[0015] Step C: Conducting primary sanding on the cooked blank in Step A and the raw material mixture in Step B to obtain a primary sanded material;

[0016] Step D: Pre-burning the primary sanded material in Step C to obtain a pre-burned material;

[0017] Step E: Conducting secondary sanding on the pre-burned material in Step D, adding an adhesive during the secondary sanding, and then performing spray drying granulation to obtain a granular material;

[0018] Step F: Compressing and molding the granular material in Step E, and after sintering, obtaining the magnesium zinc ferrite magnetic core material.

[0019] It should be noted that the nickel zinc waste magnetic core includes nickel zinc products with unqualified dimensions and appearances generated during the production process. The nickel zinc in the nickel zinc waste magnetic core specifically refers to sintered ferrite whose main components include iron oxide (Fe2O3), zinc oxide (ZnO), nickel oxide (NiO) and copper oxide. In Step A, since it is the product obtained by crushing the already sintered finished product, it is called a cooked blank.

[0020] The present invention provides a preparation method of a magnesium zinc ferrite material. By using the nickel zinc waste magnetic core as part of the raw materials, cooperating with the four main components of magnesium oxide, zinc oxide, iron oxide and copper oxide, and through a specific manufacturing process, a soft magnetic material of magnesium zinc ferrite can be obtained, whose electromagnetic characteristics are similar to those of nickel zinc ferrite, but the cost is far lower than that of nickel zinc ferrite. Its performance is better than that of the existing magnesium zinc ferrite, and the cost price is also lower than that of the magnesium zinc ferrite material. Therefore, adopting the preparation method of the present invention can reduce costs and increase efficiency. It can not only improve the broadband anti-electromagnetic interference ability of the existing magnesium zinc ferrite material, making it applicable to the 10 MHz - 1000 MHz broadband, but also greatly reduce the production cost of ferrite and improve the market competitiveness.

[0021] Preferably, in Step A, after the crushing, a screening step is carried out, and the mesh number of the screening is 140 - 200 meshes, for example, it can be 140 meshes, 160 meshes, 180 meshes or 200 meshes, etc.

[0022] Optionally, the equipment used for crushing in step A includes a Raymond mill.

[0023] Preferably, the raw material for the primary sanding in step C further includes secondary components, and the secondary components include at least one of MnO, Co2O3, Bi2O3, and NiO.

[0024] In the present invention, through a reasonably optimized process, a large proportion of nickel-zinc waste magnetic cores in the production process are utilized as raw materials. Combining the reasonable ratio effects of the main components (iron oxide, zinc oxide, magnesium oxide, and copper oxide) and the secondary components, a magnesium-zinc ferrite soft magnetic material with the effect of cost reduction and efficiency improvement can be obtained.

[0025] Preferably, based on the total mass of the raw material mixture and the secondary components being 100%, the mass content of iron oxide in the raw material mixture is 67.05 - 71.21%, for example, it can be 67.05%, 67.5%, 68%, 68.5%, 69%, 69.5%, 70%, 70.5%, 71%, or 71.21%, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0026] Preferably, based on the total mass of the raw material mixture and the secondary components being 100%, the mass content of zinc oxide in the raw material mixture is 17.1 - 21.41%, for example, it can be 17.1%, 17.5%, 18%, 18.5%, 19%, 20%, or 21.41%, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0027] Preferably, based on the total mass of the raw material mixture and the secondary components being 100%, the mass content of magnesium oxide in the raw material mixture is 2.2 - 8.98%, for example, it can be 2.2%, 2.3%, 2.5%, 3%, 4%, 6%, 7%, 8%, or 8.98%, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0028] Preferably, based on the total mass of the raw material mixture and the secondary components being 100%, the mass content of copper oxide in the raw material mixture is 3.1 - 4.9%, for example, it can be 3.1%, 3.3%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, or 4.9%, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0029] Preferably, based on the total mass of the raw material mixture and the auxiliary components being 100%, the mass content of MnO in the auxiliary components is 1.0 - 4.3%, for example, it can be 1.0%, 1.5%, 2%, 2.5%, 3%, 4% or 4.3%, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0030] Preferably, based on the total mass of the raw material mixture and the auxiliary components being 100%, the mass content of Co2O3 in the auxiliary components is 0.01 - 0.31%, for example, it can be 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3% or 0.31%, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0031] Preferably, based on the total mass of the raw material mixture and the auxiliary components being 100%, the mass content of Bi2O3 in the auxiliary components is 0.05 - 0.3%, for example, it can be 0.05%, 0.08%, 0.1%, 0.15%, 0.2%, 0.25% or 0.3%, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0032] Preferably, based on the total mass of the raw material mixture and the auxiliary components being 100%, the mass content of NiO in the auxiliary components is 0 - 5.1%, for example, it can be 0%, 1%, 2%, 3%, 4%, 5% or 5.1%, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable, where 0% indicates no addition of NiO.

[0033] Preferably, in step C, the mass ratio of the cooked blank to the raw material mixture is (1 - 4):1, for example, it can be 1:1, 2:1, 3:1 or 4:1, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0034] In the present invention, if the mass ratio of the cooked blank to the raw material mixture in step C is too low, the cost reduction effect will not be obvious.

[0035] Preferably, during the first sanding process in step C, the mass ratio of the material, the balls and the water is 1:(4 - 7):(1 - 1.2), where the selection range of the balls (4 - 7) can be, for example, 4, 5, 6 or 7, etc., and the selection range of the water (1 - 1.2) can be, for example, 1, 1.05, 1.1, 1.15 or 1.2, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0036] In the present invention, the purpose of the primary grinding is mainly to make the raw material mixture more uniform. Since there are significant differences between the particles of the cooked blank and the raw material, grind for a period of time first, and then take the slurry for actual composition analysis. Here, the composition analysis adopts the X-Tay analysis method. According to the composition analysis results, add some main components and / or auxiliary components to correct the deviation between the actual composition and the target formula, so that the final ratio of the granular material is as close as possible to the target formula.

[0037] Preferably, the time of the primary grinding described in step C is 3 to 7 h. For example, it can be 3 h, 4 h, 5 h, 6 h, 7 h, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0038] Preferably, the pre-burning temperature described in step D is 930 to 1000 °C. For example, it can be 930 °C, 950 °C, 980 °C, 990 °C, 1000 °C, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0039] Preferably, the pre-burning time described in step D is 6 to 10 h. For example, it can be 6 h, 7 h, 8 h, 9 h, 10 h, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0040] Optionally, the equipment used for pre-burning described in step D includes a rotary kiln.

[0041] Preferably, the binder described in step E includes an aqueous solution of polyvinyl alcohol, and the mass concentration of the aqueous solution of polyvinyl alcohol is 5 to 10%. For example, it can be 5%, 6%, 7%, 8%, 9%, 10%, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0042] Preferably, during the secondary grinding described in step E, the mass ratio of the material, the balls, and the water is 1:(4 - 6):(1 - 12). The selection range of the balls (4 - 6) can be, for example, 4, 5, or 6, etc., and the selection range of the water can be, for example, 1, 2, 4, 5, 8, 10, or 12, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0043] Preferably, the time of the secondary grinding described in step E is 1 to 5 h. For example, it can be 1 h, 2 h, 3 h, 4 h, 5 h, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0044] Preferably, in step E, the average particle size of the product after the second sanding is 0.6 - 2.5 μm. For example, it can be 0.6 μm, 0.65 μm, 0.7 μm, 0.9 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, etc., but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0045] Preferably, the sintering temperature in step F is 1040 - 1190 °C. For example, it can be 1040 °C, 1060 °C, 1080 °C, 1100 °C, 1150 °C, 1190 °C, etc., but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0046] Preferably, the sintering time in step F is 16 - 48 h. For example, it can be 16 h, 20 h, 24 h, 28 h, 32 h, 38 h, 40 h, 48 h, etc., but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0047] As a preferred technical solution of the present invention, the preparation method specifically includes:

[0048] Step a: Crushing the nickel - zinc waste magnetic core and screening to obtain a green blank.

[0049] Step b: Mixing iron oxide, zinc oxide, magnesium oxide, and copper oxide to obtain a raw material mixture.

[0050] Step c: Subjecting the green blank in step a and the raw material mixture in step b to primary sanding at a mass ratio of (1 - 4):1, and performing formula correction and adding secondary components during the primary sanding to obtain a primary sanded material; wherein, the secondary components include at least one of MnO, Co₂O₃, Bi₂O₃, and NiO.

[0051] Step d: Pre - sintering the primary sanded material in step c at 930 - 1000 °C to obtain a pre - sintered material.

[0052] Step e: Subjecting the pre - sintered material in step d to secondary sanding, adding an aqueous solution of polyvinyl alcohol during the secondary sanding, and then performing spray drying granulation to obtain granular material.

[0053] Step f: Compressing and molding the granular material in step e, and after sintering, obtaining the magnesium - zinc ferrite material.

[0054] The present invention does not specifically limit the pressed and molded blank, which can be of different shapes and sizes.

[0055] In the second aspect, the present invention provides a magnesium - zinc ferrite material, which is prepared by the preparation method described in the first aspect.

[0056] The numerical ranges described in the present invention include not only the point values exemplified above, but also any point values between the above numerical ranges that are not exemplified. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the described ranges.

[0057] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0058] The present invention provides a preparation method of a magnesium-zinc ferrite material. Using nickel-zinc waste magnetic cores as partial raw materials and combining four main components of magnesium oxide, zinc oxide, iron oxide, and copper oxide, through a specific manufacturing process, a soft magnetic magnesium-zinc ferrite material with electromagnetic properties similar to those of nickel-zinc ferrite but with a cost far lower than that of nickel-zinc ferrite can be obtained. Its performance is superior to that of the existing magnesium-zinc ferrite, and the cost price is also lower than that of the magnesium-zinc ferrite material. Therefore, the use of the preparation method of the present invention can reduce costs and increase efficiency. It can not only improve the broadband anti-electromagnetic interference ability of the existing magnesium-zinc ferrite material, making it applicable to the 10 MHz - 1000 MHz broadband, but also significantly reduce the production cost of the ferrite and improve the market competitiveness. Specific Embodiments

[0059] The technical solution of the present invention will be further described below through specific embodiments.

[0060] The following Examples 1 - 12 prepare ferrite materials according to the composition and ratio of the main components and auxiliary components in Table 1.

[0061] Table 1

[0062]

[0063] Example 1

[0064] This example provides a preparation method of a magnesium-zinc ferrite material, which specifically includes:

[0065] Step A: Collect nickel-zinc waste magnetic cores on the production line, and then use a Raymond mill to crush the nickel-zinc waste magnetic cores. Control the particle size by the size of the air damper, and set a 160-mesh sieve at the outlet for sieving. The coarse particle materials are returned to the crusher until all the waste magnetic cores are completely crushed to obtain crushed particle materials, denoted as cooked blank materials;

[0066] Step B: Weigh the four main components of iron oxide, zinc oxide, magnesium oxide, and copper oxide respectively according to the main components and ratio corresponding to Example 1 in Table 1 for mixing to obtain raw material mixtures;

[0067] Step C: Mix the cooked blank obtained in Step A with the raw material mixture obtained in Step B in a mass ratio of 1:1, add the auxiliary components as shown in Table 1, and then perform primary sand grinding using a vibration mill. The ratio of material:ball:water for primary sand grinding is 1:5:1. During the primary sand grinding process, first grind for 3 hours, then take the slurry and perform actual component analysis using the X-Tay analysis method. Add some raw materials according to the component analysis results to correct the deviation between the actual components and the target formula, and obtain the primary sand ground material.

[0068] Step D: Pre-burn the sand ground material obtained in Step C using a rotary kiln at a pre-burning temperature of 970 °C for 8 hours to obtain the pre-burned material;

[0069] Step E: Put the pre-burned material obtained in Step D into a vibration ball mill for secondary sand grinding. The ratio of material:ball:water for secondary sand grinding is 1:4:1. Add an adhesive during the sand grinding process. The adhesive is an aqueous solution of polyvinyl alcohol (PVA) with a mass concentration of 7%, and then perform spray drying granulation to obtain the granular material;

[0070] Step F: Add zinc stearate accounting for 0.1% of the weight of the granular material obtained in Step E, stir evenly, and press it into a green body at a molding pressure of 5 MPa. Specifically, it is a ring with an outer diameter of 25 mm, an inner diameter of 15 mm, and a height of 7 mm; then put the green body into an air kiln for sintering at a sintering temperature of 1140 °C for 16 hours to obtain the sintered ferrite.

[0071] Example 2 - 4

[0072] The difference from Example 1 is that the main components and auxiliary components are replaced with the corresponding main components and auxiliary components in Examples 2 - 4 in Table 1. The remaining parameters are exactly the same as those in Example 1.

[0073] Example 5

[0074] This example provides a method for preparing a magnesium zinc ferrite material, which specifically includes:

[0075] Step A: Collect the nickel zinc waste magnetic cores on the production line, and then use a Raymond mill to crush the nickel zinc waste magnetic cores. Control the particle size by the size of the air damper, and set a 200-mesh sieve at the outlet for sieving. The coarse granular materials are returned to the crusher until all the waste magnetic cores are completely crushed to obtain the crushed granular materials, denoted as the cooked blank;

[0076] Step B: Weigh the four main components of iron oxide, zinc oxide, magnesium oxide, and copper oxide respectively according to the main components and ratios corresponding to Example 1 in Table 1, and mix them to obtain the raw material mixture;

[0077] Step C: Mix the cooked blank obtained in Step A and the raw material mixture obtained in Step B in a mass ratio of 1:1, add the auxiliary components as shown in Table 1, and then perform primary sand grinding using a vibratory mill. The ratio of material:ball:water for primary sand grinding is 1:4:1. During the primary sand grinding process, first grind for 2.5 hours, then take the slurry and perform actual component analysis using the X-Tay analysis method. Add some raw materials according to the component analysis results to correct the deviation between the actual components and the target formula, and obtain the primary sand ground material.

[0078] Step D: Pre-burn the sand ground material obtained in Step C using a rotary kiln at a pre-burning temperature of 980 °C for 8 hours to obtain the pre-burned material;

[0079] Step E: Put the pre-burned material obtained in Step D into a vibratory ball mill for secondary sand grinding. The ratio of material:ball:water for secondary sand grinding is 1:4:1. Add a binder during the sand grinding process. The binder is an aqueous solution of polyvinyl alcohol (PVA) with a mass concentration of 7%, and then perform spray drying granulation to obtain the granular material;

[0080] Step F: Add zinc stearate accounting for 0.1% of the weight of the granular material obtained in Step E, stir evenly, and press into a green body at a forming pressure of 5 MPa. Specifically, it is an annular shape with an outer diameter of 25 mm, an inner diameter of 15 mm, and a height of 7 mm; then put the green body into an air kiln for sintering at a sintering temperature of 1190 °C for 16 hours to obtain the sintered ferrite.

[0081] Examples 6 - 12

[0082] The difference from Example 5 is that the main components and auxiliary components are replaced with the corresponding main components and auxiliary components in Examples 6 - 12 in Table 1. The remaining parameters are exactly the same as those in Example 5.

[0083] Comparative Example 1

[0084] This comparative example provides a method for preparing an existing magnesium-zinc-based ferrite, including:

[0085] Add 49.8 mol% of Fe3O4, 24.4 mol% of MgO, and 25.8 mol% of ZnO as the main components, and add 3.4 wt% of CuO and 0.8% of MnCO3 as the secondary components. Mix and grind the above main and secondary components; pre-burn in an air kiln at a pre-burning holding temperature of 960 °C ± 10 °C for 2 hours; mix, sand mill, and spray granulate the pre-burned powder materials and auxiliary materials such as polyvinyl alcohol, dispersant, and defoamer, and control its average particle size to be 80 μm to 300 μm; press the granular materials into a toroidal core with dimensions of H25 mm × 15 mm × 7.0 mm. Gradually heat up the above core in an air kiln, hold at 1100 °C ± 10 °C for 3.5 hours, and then gradually cool to obtain a magnesium-zinc ferrite core.

[0086] Comparative Example 2

[0087] This comparative example provides a preparation method of an existing magnesium-zinc ferrite (DM65), including:

[0088] Weigh 66.68 wt% of Fe2O3, 16.53 wt% of ZnO, 5.59 wt% of MgO, 2.39 wt% of MnO, and 8.81 wt% of CuO as the main components and add them, and then add 0.15 wt% of CaCO3 and 0.1% of Bi2O3 as the secondary components. Mix and grind the above main and secondary components; pre-burn in an air kiln at a pre-burning holding temperature of 980 °C ± 10 °C for 4 hours; mix, sand mill, and spray granulate the pre-burned powder materials and auxiliary materials such as polyvinyl alcohol, dispersant, and defoamer, and control its average particle size to be 50 μm to 300 μm; press the granular materials into a toroidal core with dimensions of H25 mm × 15 mm × 7.0 mm. Gradually heat up the above core in an air kiln, hold at 1250 °C ± 10 °C for 3.5 hours, and then gradually cool to obtain a magnesium-zinc ferrite (DM65) core.

[0089] Comparative Example 3

[0090] This comparative example provides a preparation method of an existing nickel-zinc ferrite (DN85H), including:

[0091] Weigh 66.38 wt% of Fe2O3, 20.75 wt% of ZnO, 8.88 wt% of NiO, and 3.99 wt% of CuO as the main components and add 0.1 wt% of CaCO3 and 0.2% of Bi2O3 as the secondary components. Mix and grind the above main and secondary components; pre-burn them in an air kiln at a pre-burning holding temperature of 950 °C ± 10 °C for 4 hours; mix, sand mill, and spray granulate the pre-burned powder materials with auxiliary materials such as binder (e.g., polyvinyl alcohol), dispersant, and defoamer, and control the average particle size to be 50 μm - 300 μm; press the granular materials into a toroidal core with dimensions of H25 mm × 15 mm × 7.0 mm. Gradually increase the temperature of the above core in an air kiln, hold it at 1080 °C ± 10 °C for 3.5 hours, and then gradually cool it to obtain a nickel-zinc ferrite (DN85H) core.

[0092] Performance Test

[0093] For the ferrites provided in the above examples and comparative examples, use a copper wire with a diameter of Φ0.35 mm, a number of turns N = 20 Ts, and under the condition of U = 0.25 V, use an E4991A type LCR tester to measure the inductance of the magnetic ring sample to obtain the initial permeability μi; use an Agilent E4990A impedance analyzer to measure the impedance Z value under the conditions of Φ1.0 mm and a number of turns = 1 TS; use an SY-8258 type B-H analyzer to measure the saturation magnetic induction intensity Bs (50 Hz / 4000 A / m) of the sample, use an LCR-4225 type inductance analyzer and a special oven to measure the Curie temperature Tc of the sample; use an Agilent4339B high resistance meter to measure the insulation surface resistance value R at both ends of Ф25*15*8 mm and calculate the resistivity ρ. The test results are shown in Table 2.

[0094] Table 2

[0095]

[0096] Analysis:

[0097] As can be seen from Table 1 and Table 2, when the magnesium-zinc target main components are determined, adjust the overall composition according to the composition of the nickel-zinc waste core, synergistically proportion the main components with specific contents, and then use specific proportions of auxiliary additives (i.e., secondary components) to assist the main components to further optimize the performance, so that the magnesium-zinc ferrite of the present invention can maintain a wide-frequency high permeability of 1 kHz - 1 MHz, and at the same time has a high Curie temperature and a resistivity greater than or equal to 10 5 Ω·m (DC500V, spacing 10 mm), and its impedance performance is higher than that of the existing magnesium-zinc ferrites, can be equivalent to the existing nickel-zinc ferrites, but the price is lower than that of the nickel-zinc ferrites.

[0098] It can be seen from the data structures of Table 1 and Table 2 that an increase in zinc content and magnesium content can improve the magnetic permeability, but will reduce the Curie temperature and frequency characteristics; an increase in manganese content will improve the magnetic permeability and Curie temperature, but the high-frequency performance will decline at the same time; an increase in nickel content can increase the Curie temperature and also improve the high-frequency performance, but the magnetic permeability will decrease; Co2O3 can compensate for the negative magnetocrystalline anisotropy constant K1 of the ferrite, so adding a certain content of Co2O3 can improve the temperature characteristics of the material's magnetic permeability and improve the high-frequency impedance performance. However, if the dosage of Co2O3 exceeds a specific ratio, it will cause lattice distortion and lead to a decrease in the initial magnetic permeability; in CaCO3, because Ga 2+ has a relatively large ionic radius and generally does not enter the interior of the lattice, but only forms a high-resistance grain boundary layer at the lattice boundary. Therefore, adding a certain content of CaCO3 can increase the resistivity and reduce the eddy current loss. Adding a certain content of Bi2O3 can play a role in reducing the melting point and densification.

[0099] It can be seen from the performance results of Examples 1-12 that the present invention adopts a reasonably optimized preparation process, uses a large amount of nickel-zinc waste magnetic cores on the production line as raw materials, and combines with appropriate main and auxiliary components, making the ferrite have excellent performance in all aspects. It can be used as a material replacement for anti-electromagnetic interference (EMI) applications such as inductors or filters, and also greatly reduces the production cost, thus winning the market competitiveness.

[0100] It can be seen from the performance results of Examples 1-12 and Comparative Examples 1-3 that the ferrite prepared by the method of the present invention has performance close to that of the existing anti-EMI nickel-zinc ferrite and is superior to the existing magnesium-zinc ferrite, not only improving the performance but also effectively reducing the production cost.

[0101] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A preparation method of a magnesium zinc ferrite material, characterized in that, The preparation method includes: Step A: Crushing the nickel-zinc waste magnetic core to obtain a cooked blank; Step B: Mixing iron oxide, zinc oxide, magnesium oxide, and copper oxide to obtain a raw material mixture; Step C: Conducting primary sanding on the cooked blank described in Step A and the raw material mixture described in Step B to obtain a primary sanded material; Step D: Pre-burning the primary sanded material described in Step C to obtain a pre-burned material; Step E: Conducting secondary sanding on the pre-burned material described in Step D, adding a binder during the secondary sanding process, and then performing spray drying granulation to obtain granular material; Step F: Compressing and molding the granular material described in Step E, and after sintering, obtaining the magnesium-zinc ferrite material.

2. The preparation method according to claim 1, characterized in that, In Step A, a sieving step is performed after the crushing, and the mesh number of the sieving is 140 - 200 meshes.

3. The preparation method according to claim 1 or 2, characterized in that, The raw materials for the primary sanding described in Step C further include secondary components, and the secondary components include at least one of MnO, Co2O3, Bi2O3, and NiO; Preferably, based on the total mass of the raw material mixture and the secondary components being 100%, the mass content of iron oxide in the raw material mixture is 67.05 - 71.21%; Preferably, based on the total mass of the raw material mixture and the secondary components being 100%, the mass content of zinc oxide in the raw material mixture is 17.1 - 21.41%; Preferably, based on the total mass of the raw material mixture and the secondary components being 100%, the mass content of magnesium oxide in the raw material mixture is 2.2 - 8.98%; Preferably, based on the total mass of the raw material mixture and the secondary components being 100%, the mass content of copper oxide in the raw material mixture is 3.1 - 4.9%; Preferably, based on the total mass of the raw material mixture and the secondary components being 100%, the mass content of MnO in the secondary components is 1.0 - 4.3%; Preferably, based on the total mass of the raw material mixture and the secondary components being 100%, the mass content of Co2O3 in the secondary components is 0.01 - 0.31%; Preferably, based on the total mass of the raw material mixture and the secondary components being 100%, the mass content of Bi2O3 in the secondary components is 0.05 - 0.3%; Preferably, based on the total mass of the raw material mixture and the secondary components being 100%, the mass content of NiO in the secondary components is 0 - 5.1%.

4. The preparation method according to any one of claims 1 to 3, characterized in that, In Step C, the mass ratio of the cooked blank to the raw material mixture is (1 - 4):

1.

5. The preparation method according to any one of claims 1-4, characterized in that, During the primary sanding described in Step C, the mass ratio of the material, balls, and water is 1:(4 - 7):(1 - 1.2); Preferably, the time for the primary sanding described in Step C is 3 - 7 h.

6. The preparation method according to any one of claims 1-5, characterized in that, The temperature for the pre-burning described in Step D is 930 - 1000 °C; Preferably, the time for the pre-burning described in Step D is 6 - 10 h.

7. The preparation method according to any one of claims 1-6, characterized in that, The binder described in Step E includes an aqueous solution of polyvinyl alcohol, and the mass concentration of the aqueous solution of polyvinyl alcohol is 5 - 10%; Preferably, during the secondary sanding described in Step E, the mass ratio of the material, balls, and water is 1:(4 - 6):(1 - 12); Preferably, the time for the secondary sanding described in Step E is 1 - 5 h; Preferably, in step E, the average particle size of the product after the secondary sanding is 0.6 to 2.5 μm.

8. The preparation method according to any one of claims 1-7, characterized in that, The sintering temperature in step F is 1040 to 1190 °C; Preferably, the sintering time in step F is 16 to 48 h.

9. The preparation method according to any one of claims 1-8, characterized in that, The preparation method specifically includes: Step a: Crushing the nickel-zinc waste magnetic core and obtaining a green blank after sieving; Step b: Mixing iron oxide, zinc oxide, magnesium oxide and copper oxide to obtain a raw material mixture; Step c: Subjecting the green blank in step a and the raw material mixture in step b to primary sanding at a mass ratio of (1 to 4):1, performing formula correction and adding secondary components during the primary sanding to obtain a primary sanding material; wherein, the secondary components include at least one of MnO, Co2O3, Bi2O3 and NiO; Step d: Pre-sintering the primary sanding material in step c at 930 to 1000 °C to obtain a pre-sintered material; Step e: Subjecting the pre-sintered material in step d to secondary sanding, adding an aqueous solution of polyvinyl alcohol during the secondary sanding, and then performing spray drying granulation to obtain a granular material; Step f: Compressing and molding the granular material in step e, and obtaining the magnesium-zinc ferrite material after sintering.

10. A magnesium zinc ferrite material, characterized in that, The magnesium-zinc ferrite material is prepared by the preparation method according to any one of claims 1-9.

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